(noun) The feeling of euphoria experienced after any amount, though usually intense amount, of laughter.
Numbness in the legs, arms, head, or any other area of the body may be an effect.
The effects are much like that experienced during and after an adrenaline rush.

After John heard that Obama was still in office, he laughed for ten minutes straight.
When he stood up, he fell over from his legs being numb from laughtershock.

Similar to the aftershocks of a large earthquake, laughtershocks are small and quick bursts of giggles after a large, initial laugh, usually responsible for a audience missing a large percentage of secondary jokes.